Hoods and suction blowers are used to collect vapors, greases and odors from cooking ranges, fryers, broilers and other cooking equipment and discharge these pollutants to the outside atmosphere. The hoods are positioned above the cooking equipment to collect the pollutants with the air moving through the hoods. Fans in the system operate to draw the hot air and cooking pollutants through the hood and discharge the air and pollutants to the outside atmosphere. In commercial installations, large amounts of smoke and grease laden air are discharged into the atmosphere. This practice results in air pollution and large amounts of heat loss as the heat in the discharged air is not utilized. In some installations, the air is recirculated into the environment after it is passed through grease filters and fiber air filters. An example of this system is shown by Jensen in U.S. Pat. No. 3,260,189.
Baffle separators having conical louver impingement structures are used for oil and water droplet elimination from air. The baffle structure operates to separate particulate materials and droplets from the air moving through the separator chamber. An example of a conical louver impingement separator is shown in page 34 of the Air Pollution Manula - Part II, Control Equipment published by the American Industrial Hygiene Association. Air cleaners having inclined vanes or deflectors have been used to provide the air with a circular motion so that particulates entrained in the air will be separated from the air by centrifugal forces. Examples are shown by Bull in U.S. Pat. No. 1,743,521 and Moynan in U.S. Pat. No. 1,867,465.
A series of fixed helical elements are used in mixing machines to mix material flowing through a passage. Examples of this structure are shown in U.S. Pat. No. 3,286,992; No. 3,664,638 and No. 3,704,006.